Chemotherapeutics are the major treatment options for cancer. Although we cannot underestimate the importance of the chemotherapeutic drugs, their systemic toxicity is an important limiting factor for their use. Therefore, altering the biodistribution of the therapeutics can be an important step in treating the cancer patients. Thus, there is a growing interest in developing smart, targeted, stimuli responsive, drug delivery vehicles employing nanotechnalogy. The vehicles are often engineered to deliver the theranostics to the tumor microenvironment (extracellular matrix) or intracellular environment (e.g. cytosol, nucleus, mitochondria). The physiochemical changes in the cancerous tissues (e.g. leaky vasculature, proteins overexpression on the cell surface, overexpression of proteolytic enzymes, increased reducing agents concentration, decreased pH, and hypoxia) offer tremendous opportunities for selectively targeting the malignancies. Polymersomes are robust polymeric vesicles which have shown promising drug delivery capabilities. Both hydrophilic and hydrophobic compounds can be loaded to the vesicles. The polymersome's building blocks can be chemically manipulated to provide them with the optimum release profile. Furthermore, the surface of the polymersomes can be decorated with targeting moieties such as peptides, antibodies, or small molecules. We have developed smart, targeted, stimuli responsive polymersomes to combat pancreatic and prostate cancers.